One of the most exciting developments in astronomy in the last couple of decades has been the discovery and study of planets around stars other than our Sun. These worlds outside our Solar System are known as exoplanets. Today, we know that exoplanets can be found in a whole host of configurations and around many different types of stars. Yet astronomers are still trying to determine exactly what conditions make the formation of planets viable - or not.

A new study using observations from the Chandra X-ray Observatory is helping to provide insight about the likelihood of planets forming around stars less massive and much younger than the Sun. The TW Hydra group of stars contains these smaller and fainter stars, with ages of about 8 million years old. By contrast, our Sun is about 4.5 billion years old. The researchers wanted to look at stars of this juvenile age because this is when it is thought that planets would begin to form and develop.

The researchers found that even these more diminutive stars can unleash a damaging amount of X-rays, potentially destroying planet-forming disks that surround them. This result suggests that X-ray output should be factored in when thinking about how hospitable low-mass stars really are for planets surviving around them.
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When the star that created this supernova remnant exploded in 1572, it was so bright that it was visible during the day. And though he wasn't the first or only person to observe this stellar spectacle, the Danish astronomer Tycho Brahe wrote a book about his extensive observations of the event, gaining the honor of it being named after him.

In modern times, astronomers have observed the debris field from this explosion - what is now known as Tycho's supernova remnant - with many telescopes including the Chandra X-ray Observatory. Since much of the material being flung out from the shattered star has been heated by shock waves - similar to sonic booms from supersonic planes - passing through it, the remnant glows strongly in X-ray light.

Astronomers used Chandra observations from 2000 through 2015 to create the longest movie of the Tycho remnant's X-ray evolution over time - the first such movie of Tycho ever made. This movie shows that the expansion from the explosion is still continuing about 450 years after Tycho Brahe and others witnessed the event.

By combining the X-ray data with some 30 years of observations in radio waves with the VLA, also producing a movie, astronomers have used these data to learn new things about this supernova and its remnant.

So grab some popcorn and enjoy this early summer movie. It will be unlike any you'll see in the theater!
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As their reputation -- and very name - suggest, black holes are black. That is, once light passes a certain threshold of a black hole, called the event horizon, it never returns. This should make them virtually impossible to find. However, astronomers have found many black holes both here in our Milky Way galaxy and beyond. How is that possible? The answer is that regions immediately surrounding the black hole are often very bright in different types of light, including X-rays. That's because the black hole's immense gravitational pull can pull material away from a companion star at a high rate. This can create a swirling disk of heated material, generate enormous jets that reach across vast distances of space, or produce other telltale signs that we can observe with modern telescopes.

But what if a black hole is just sitting in space quietly, pulling in material at an unusually slow rate? It turns out that this might be more common than astronomers thought. A new result shows that a source within our Galaxy is actually a very quiet black hole - one that was never identified before as a black hole until now. It took data from many telescopes including Chandra, Hubble and several radio observatories to piece together all of the necessary information.

A team of researchers is now very confident that this source - known as VLA J2130+12 for short - contains a black hole a few times the mass of the Sun. This result suggests that the Milky Way galaxy could have thousands or even millions of these silent black holes. To find out if this is the case, astronomers will be looking to find them.
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Black holes come in different sizes. The largest, or supermassive, black holes can contain hundreds of thousands times the mass of the Sun up to billions of times its mass and typically reside in the centers of galaxies. Sometimes, however, astronomers find black holes in somewhat unusual places.

Take, for example, the object known as XJ1417+52. First discovered in observations from Chandra and XMM-Newton over a decade ago, this object has some interesting properties. To begin with, astronomers think this object may fall right at the boundary between supermassive black holes and the intermediate-mass category. As their name suggest, the latter class are black holes of medium size in between stellar mass black holes and supermassive ones. X-rays from both Chandra and XMM-Newton show that XJ1417+52 gave off an extraordinary amount of X-rays. This and other pieces of evidence suggest that XJ1417+52 contains about 100,000 times the mass of the Sun.

What makes this object even more interesting is its location. Rather than being in the center of its host galaxy, it is located on its northern edge. Astronomers think this could have happened when a smaller galaxy with XJ1417+52 at its center collided with a larger galaxy. Since these two galaxies are still in the process of merging, the two black holes have yet to coalesce into one bigger black hole, but may do so millions or billions of years from now.
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A group of unusual giant black holes may be consuming excessive amounts of matter, according to a new study using NASA's Chandra X-ray Observatory. This finding may help astronomers understand how the largest black holes were able to grow so rapidly in the early Universe.

Astronomers have known for some time that supermassive black holes - with masses ranging from millions to billions of times the mass of the Sun and residing at the centers of galaxies - can gobble up huge quantities of gas and dust that have fallen into their gravitational pull. As the matter falls towards these black holes, it glows with such brilliance that they can be seen billions of light years away. Astronomers call these extremely ravenous black holes "quasars."

This new result suggests that some quasars are even more adept at devouring material than previously thought, about five to ten times the rate of typical quasars. A team of astronomers examined data from Chandra for 51 quasars that are located at a distance between about 5 billion and 11.5 billion light years from Earth. Based on their findings, the researchers think some of these quasars contain black holes that are surrounded by a thick, donut-shaped disk of material. This torus would block much of the light - including X-rays and ultraviolet light -- that would otherwise be observed by Chandra and other telescopes. The important implication for these thick-disk quasars is that they may be harboring black holes that are growing an extraordinarily rapid rate.
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Galaxy clusters are the largest structures in the Universe held together by gravity. They consist of huge reservoirs of hot gas that glow in X-ray light as well as hundreds or even thousands of individual galaxies, plus unseen dark matter. Understanding how clusters grow is critical to tracking how the Universe itself evolves over time.

A new result involving the system named Abell 1033 is providing another piece to this astronomical puzzle. Located about 1.6 billion light years from Earth, Abell 1033 is the site of the collision of two galaxy clusters. By combining X-ray data from Chandra along with radio and optical data, astronomers have found evidence that Abell 1033 is what is called a "radio phoenix." What does this mean? Astronomers think a supermassive black hole close to the center of Abell 1033 underwent an eruption in the past. Streams of high-energy electrons filled a region hundreds of thousands of light years across and produced a cloud of bright radio emission. This cloud faded over a period of millions of years as the electrons lost energy and the cloud expanded.

The radio phoenix emerged when another cluster of galaxies slammed into the original cluster, sending shock waves through the system. These shock waves, similar to sonic booms produced by supersonic jets, passed through the dormant cloud of electrons. The shock waves compressed the cloud and re-energized the electrons, which caused the cloud to once again shine at radio frequencies. Just as the phoenix rises from its ashes in the stories of mythology, so too does it appear Abell 1033 has undergone an amazing rebirth.
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Astronomers have known for quite some time that supermassive black holes influence the growth of galaxies they live in, but they have been trying to figure out exactly how. A new study of over 200 galaxy clusters using data from NASA's Chandra X-ray Observatory is an important step in that direction. Researchers used Chandra to look at some of the largest known galaxies lying in the middle of galaxy clusters. These galaxies are embedded in enormous atmospheres of hot gas. This hot gas should cool and many stars should then form. However, observations show that something is hindering the star birth. The latest study suggests that a phenomenon referred to as cosmic precipitation may be playing a critical role. Cosmic precipitation is not rain, sleet, or snow. Rather, it is a mechanism that allows hot gas to produce showers of cool gas clouds that fall into a galaxy. Some of these clouds form stars, but others rain onto the supermassive black hole, triggering jets of energetic particles that push against the falling gas and reheat it. This prevents more stars from forming. This cycle of cooling and heating creates a feedback loop that regulates the growth of the galaxies. Future studies will test whether this precipitation-black hole feedback process also regulates star formation in smaller galaxies, including our own Milky Way galaxy.
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When something, like a star or a planet, wanders too close to a black hole, it's usually not good news for that object. The gravitational forces of the black hole can tear apart the star or planet, creating a debris field, much of which will ultimately circle toward the black hole and pass beyond its point of no return. Astronomers call these events "tidal disruptions".

In recent years, astronomers have found evidence for multiple different cases for tidal disruption around various black holes. A newly discovered tidal disruption, however, is providing scientists with new details about exactly what happens when a black hole rips apart a star. This event, called ASASSN-14li, occurred in a galaxy about 290 million light years from Earth. This makes this the closest tidal disruption to Earth in a decade.
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In astronomy, it is often difficult to figure out exactly far away objects are. For objects in our Solar System and nearby stars, astronomers can use reliable methods involving geometry. However, these techniques cannot be applied to objects beyond our immediate cosmic neighborhood. There are some rare circumstances where relatively simple geometric techniques can be used to determine distances to more far-flung objects.

This is the case of Circinus X-1, a system in which a neutron star is in orbit around a massive star. In 2013, astronomers watched as Circinus X-1 erupted in a giant burst of X-rays. Afterwards, they used NASA's Chandra X-ray Observatory and ESA's XMM-Newton to observe what happened next. The scientists now report that they see a set of four rings that appear as circles around Circinus X-1. What are these are these rings and what do they do? These rings are light echoes, similar to sound echoes that we may experience here on Earth. Instead of sound waves bouncing off a canyon wall, the echoes around Circinus X-1 are produced when a burst of X-rays from the star system ricochets off of clouds of dust between Circinus X-1 and Earth.

By combining the light echoes that Chandra detects with radio data from the Mopra telescope in Australia, which determined the distance to the intervening clouds, astronomers can estimate the distance to Circinus X-1 using relatively simple geometry. The light echo method generates a distance of 30,700 light years. The observation thus settles a large difference amongst previous results, one similar to this work and one indicating a much smaller distance of about 13,000 light years.
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One of the most recognizable constellations in the sky is Orion, the Hunter. Among Orion's best-known features is the "belt," consisting of three bright stars in a line, each of which can be seen without a telescope. The westernmost star in Orion's belt is known officially as Delta Orionis. (Since it has been observed for centuries by sky-watchers around the world, it also goes by many other names in various cultures, like "Mintaka".) Modern astronomers know that Delta Orionis is not simply one single star, but rather it is a complex multiple star system.

Delta Orionis is, in fact, a small stellar group with three components and five stars in total. Two of the stars are single stars and may give off small amounts of X-rays. The third component on the other hand, has been detected as a strong X-ray source. Today, astronomers know that this component, called Delta Orionis A, is itself a triple star system.

In Delta Orionis A, two closely separated stars orbit around each other every 5.7 days, while a third star orbits this pair with a period of over 400 years. The more massive, or primary, star in the closely-separated stellar pair weighs about 25 times the mass of the Sun. The less massive, or secondary star, weighs about ten times the mass of the Sun.

The chance alignment of this pair of stars allows one star to pass in front of the other during every orbit from the vantage point of Earth. This special class of star system is known as an "eclipsing binary," and it gives astronomers a direct way to measure the mass and size of the stars.
By observing this eclipsing binary component of Delta Orionis A with NASA's Chandra X-ray Observatory for the equivalent of nearly six days, a team of researchers gleaned important information about massive stars and how their winds play a role in their evolution and affect their surroundings.

Massive stars, although relatively rare, can have profound impacts on the galaxies they inhabit. These giant stars are so bright that their radiation blows powerful winds of stellar material away, affecting the chemical and physical properties of the gas in their host galaxies. These stellar winds also help determine the fate of the stars themselves, which will eventually explode as supernovas and leave behind a neutron star or black hole.
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